docs: def sizeof(self, fields):
          """Retrieve the size in bytes of the given fields.
  
          Args::
  
            fields   sequence of field names to query
  
          Returns::
  
            total size of the fields in bytes
  
          C library equivalent : VSsizeof
                                                     """
  
          if type(fields) in [tuple, list]:
              str = ','.join(fields)
          else:
              str = fields
          n = _C.VSsizeof(self._id, str)
          _checkErr('sizeof', n, "cannot retrieve field sizes")
          return n